Recently I bought a used Webra 61 Speed with TN carb. The seller just say that the engine seems to run very little. In fact the engine looks like new with a bit "browned" piston. I mounted the engine in a Tower Hobbies 60 Trainer. The engine start easy using 0% nitro fuel, at 3 1/2 turn, and an APC 11X5 prop. after a dead stick during take off, I reopened the intake needle valve setting it to 4 turns, The plane take off and performs a 5 minute fly at 1/2 throttle withouth problems. It seems that the engine is almost new, and don't know if is necessary to complete a break in process.- I'm afraid to damage the engine if run it at full throttle. I handled the engine cylinder after landing and the engine wasn't hot. Do I perform a break in process?

P.D. The engine has a ringed piston

Just keep flying it. Avoid using full throttle for more than a few seconds if you can. Keep the needle two or three clicks on the rich side. The mid range idle can be erratic until it is fully run in.

In it's day it was the most powerful regular 61 around especially if used with the factory tuned pipe.

Hi!
First of all a 11x5 prop is way way too small! You should be using either a 11x7,5 ,11x8 or a 12x6 prop.